The following is a tabulation of some prior art that presently appears at least partly relevant:
U.S. PatentsU.S. Pat. No.Issue datePatentee5,436,672Jul. 25, 1995Medioni et. al.5,280,530Jan. 18, 1994Threw et. al.5,808,695Sep. 15, 1998Rosser et. al.5,892,554Apr. 6, 1999DiCicco et. al.5,953,076Sep. 14, 1999Astle et. al.6,993,184Jan. 31, 2006Matsugu2,773,990Dec. 11, 1956Polhemus, et. al.
U.S. Pat. Application PublicationsPat. No.Publication datePatenteeU.S. 2008/0226253Sep. 18, 2008Steinberg et.al.
Search fields 348/571, 348/580, 348/583, 348/699